With the miniaturization of wireless communication devices over the last decade, smaller antennas have become necessary to provide data connections. On-chip space is at a premium, and removal of the antenna from inside a wireless device would allow more room for transistors. This would improve the processing speed and performance of the wireless device.
In addition, as car navigation systems become more popular, there has been a growing need for an antenna that may be applied to a car window to minimize the space required for the antenna. Such an antenna needs to be transparent enough to provide good visibility for a driver.
Transparent conductors have been proposed that are suitable for multiple antenna applications. Transparent conductive material can receive and transmit signals, while maintaining the optical transparency necessary to be integrated into, for example, a display window of a wireless communication device or a vehicle window. Integrating the transparent conductor on the display window of a wireless device also screens out potential interference from electronic sources inside the device.
Some materials that have been proposed for transparent conductors suitable for antenna applications include nanowire networks, metallic mesh structures, graphene sheets, and nanoparticle-based arrays. None of these materials, alone, are capable of simultaneously optimizing all of the parameters needed to be an efficient transparent antenna. In particular, none of the proposed materials, alone, can simultaneously provide high carrier mobility, high optical transparency, and low sheet resistance, all of which are needed to provide a transparent antenna with optimal efficiency.
Transparent conductive oxides, such as Indium Tin Oxide (ITO) have also been proposed as materials for transparent antennas. However, such materials are rigid and are too brittle for antenna applications that demand robustness.
In view of the above, there is a need for a robust transparent antenna that simultaneously provides high carrier mobility, high optical transparency and low sheet resistance.